The present invention relates to the merging of two previously unrelated raster scan video signals. The present invention relates more particularly to the use of a microcomputer""s raster scan video signal to be in a standard broadcast video format, such as NTSC, PAL, or other standard system, and then to merge the microcomputer""s video with another standard broadcast video signal by various methods, including keying.
Microcomputers are used, for example, to generate graphics video in non-mergable formats.
Broadcast standard video formats such as that adopted by the National Television Standards Committee [NTSC], or the European standard, Phase Alternating Line [PAL] (hereinafter collectively referred to as NTSC), are extensively utilized for the transmission, recording and playback of real time activities.
The merging of computer graphics with an NTSC format video signal to get a single composite display has generally required considerable hardware, both cumbersome and expensive.
Computer overlay (merging) systems have been constructed, for example, in a manner allowing for external horizontal and vertical synchronization of the computer display to an NTSC composite sync signal or to individual horizontal and vertical drive signals from an external NTSC broadcast sync generator. The computer would then output individual red, blue and green signals which would in turn be connected to an external NTSC broadcast encoder (which would also be driven by the common broadcast sync generator) the output of which was a stable NTSC computer video signal. To then merge this NTSC computer video signal with another real time or recorded video signal, it has been necessary to feed the NTSC computer signal into a production switcher incorporating an additive mixing device for dissolve or a non-additive device for keying. Horizontal, vertical, and color synchronization of the two video signals has been required. In the case of the live camera NTSC video source, the camera""s synchronization reference came from a broadcast NTSC sync generator which provided all system equipment with the required external drives. In the case of a prerecorded television signal, the playback device has, for example, been connected to an externally referenced time base corrector to bring the horizontal, vertical and color elements of the playback signal into synchronization with the common NTSC sync generator. Some devices such as titling generators would key only in black and white over an NTSC video input signal. Such devices are generally single purpose and do not incorporate a general purpose computer. The system of the present invention synchronizes and cleanly merges microcomputer generated color or black and white video with an externally generated stable or unstable, color or black and white video signal. In the preferred embodiment a reverse time base correction and keying is utilized. In this manner, synchronization and keying is accomplished without, for example, the cumbersome and expensive techniques previously described.
It is thus an object of the present invention to provide a method of video synchronizing and merging which will allow a broadcaster or cablecaster to overlay their video sources such as weather radar or camera visuals with related microkeyer generated graphics, text or data.
It is another object of the present invention to provide the medical field with a method to overlay the video surveillance of a patient with current vital statistics; or a means to overlay x-rays with pertinent data prior to viewing, transmission or recording.
It is another object of the present invention to provide the industrial control and monitoring technician with a method to overlay temperature, pressure, time, etc. over a video picture of a process for immediate viewing, transmission, and/or recording; with microcomputer process control available from the microkeyer.
It is another object of the present invention to provide a method in security systems to overlay a surveillance camera with area security status readouts for immediate viewing, recording, or transmission.
It is another object of the present invention to provide the instructional environment with a method to overlay a recorded or live instructional material with relevant computer appointments for purposes of clarification, instruction, and real time interaction with the student without the need for two display sources.
It is another object of the present invention to provide the sales environment with a method to overlay catalog or store visuals with current pricing, stocking, availability, etc.
It is another object of the present invention to provide a method wherein binary data may be placed into the active display picture area for purposes of video transmission, or recording.
It is an another object of the present invention to provide a method of synchronizing and merging video signals wherein binary data displayed on a microkeyer may be easily decoded by another microkeyer utilizing to fullest advantage the synchronous nature of the microkeyer.
In accordance with the present invention, a device and method is described which teaches how to capably and efficiently merge a microcomputer video display with a stable or unstable color video source in full color using reverse time base correction.
The system efficiently synchronizes and then merges, principally by, but not limited to, keying the video of a general purpose microcomputer having video display capability with another incoming video signal from a source such as a television camera, a demodulated television tuner, a video playback device, another similarly constructed microkeyer, or an internally generated color matte or black matte signal.